feat: add gitcommit auto configuration

Set `spell`, and `textwidth` when entering a git commit.
Also automatically move to position 1:1 and enter insert mode

ftplugin/gitcommit.lua

@@ -0,0 +1,5 @@
+vim.wo.spell = true
+vim.bo.textwidth = 75
+
+vim.fn.setpos(".", { 0, 1, 1, 0 })
+vim.cmd("startinsert")